With vertical semiconductor devices in which current flows between the first and second main surfaces of the semiconductor substrate (semiconductor wafer), the semiconductor substrates are being made thinner and thinner in order to achieve improvements in characteristics (e.g., to reduce on-state voltage). In a common single-wafer-processing semiconductor manufacturing apparatus, the semiconductor substrates are transported to a metal stage having an approximately flat surface and are set on the stage by suction.
Now, thin semiconductor substrates, having a diameter of 6 inches and a thickness of 200 μm or less, for example, have reduced strength Also, when contaminants such as dust and dust particles of Si attach to the back of a semiconductor substrate and the semiconductor substrate is placed on the stage for processing or for inspection, the contaminants are sandwiched between the semiconductor substrate and the stage. If the contaminants have certain or higher hardness, the semiconductor substrate undergoes considerable stress at and around the contaminants, which may result in breakage or deformation of the semiconductor substrate.
To solve this problem, Patent Document 1 discloses an example of a semiconductor manufacturing apparatus in which a buffer made of an elastic body is interposed between the semiconductor substrate and stage. Also, Patent Documents 2 to 4 disclose examples of semiconductor manufacturing apparatuses in which holes, or the like, are formed in the surface of the stage.
Patent Document 1: Japanese Patent Application Laid-Open No. 55-43853 (1980)
Patent Document 2: Japanese Patent Application Laid-Open No. 62-199030 (1987)
Patent Document 3: Japanese Patent Application Laid-Open No. 59-135742 (1984)
Patent Document 4: Japanese Patent Application Laid-Open No 4-152512 (1992)
In the semiconductor manufacturing apparatus disclosed in Patent Document 1, the presence of the buffer, separate from the stage, is likely to deteriorate operability in processing. Also, in the semiconductor manufacturing apparatuses disclosed in Patent Documents 2 to 4, semiconductor substrates are sucked from the holes, or the like, formed in the surface of the stage Accordingly, when the holes, or the like, are large, the semiconductor substrates undergo considerable stress at and around the holes, which may also result in breakage or deformation of the semiconductor substrates.